Same drug, different delivery system. The Pentasa is released higher in the colon than mesalazine. Paradoxically, though, I have heard people with left-sided UC say they responded to it when they didn't to Mesalazine. Hope it works for you.

Judy

Moderate to severe left-sided UC (21 cm) diagnosed 2001.

Avascular necrosis in both shoulders is my "forever" gift from Entocort.